Abstract
Purpose: :
To compare the toxicity of triamcinolone acetonide (TA) and dexamethasone sodium phosphate (DEX) on human lens epithelial (HLE) cells in-vitro.
Methods: :
HLE cells were cultured in Minimum Essential Medium (MEM). Commercially available TA [(c-TA) (Kenalog®, BMS, Princeton, NJ)] was centrifuged at 5000 rpm for one minute and the supernatant was removed. The pellet was re-suspended in equivalent amounts of DMSO to produce solubulized TA (s-TA). Cells were treated with 100, 200, 500, 750, or 1000 (clinical dose) µg/mL concentrations of c-TA, s-TA, and the supernatant for 24 hours. Other HLE cells were treated with dexamethasone sodium phosphate (APP, Schaumburg, IL) at 0.05, 0.1 (clinical dose), 0.2, 0.5, 1, and 2 mg/ml. Cell viability was determined by trypan blue dye-exclusion assay. Caspase-3/7 was measured by fluorescence caspase kit.
Results: :
The mean cell viabilities of HLE after 24 hours exposure to c-TA at 1000, 750, 500, 200, and 100µg/ml were 17.3 ± 5.5 (P < 0.001), 23.2 ± 6.2 (P < 0.001), 31.8 ± 6.8 (P < 0.001), 52.9 ± 5.9 (P <0.01), and 71.1 ± 1.65 (P <0.05), respectively, compared to control untreated cells. The mean cell viabilities of HLE after exposure to s-TA at 1000, 750, 500, 200, and 100µg/ml were 19.8 ± 1.1 (P < 0.001), 28.6 ± 3.2 (P < 0.001), 38.4 ± 2.4 (P < 0.001), 77.3 ± 3.1 (P >0.05), and 80.5 ± 2.45 (P >0.05), respectively, compared to equivalent DMSO control. The supernatant alone did not reduce the viability of HLE. Caspase-3/7 activity in HLE cells increased significantly after treatment with s-TA at 750, and 1000 µg/mL.The mean cell viabilities of HLE after 24 hours exposure to DEX at 2 , 1, 0.5, 0.2, 0.1, and 0.05 mg/ml were 14.8 ± 0.6 (P < 0.001), 23.6 ± 0.1 (P < 0.001), 80.1 ± 0.9 (P < 0.001), 92.4 ± 0.3 (P > 0.05), 93.1 ± 2.1 (P > 0.05), and 93.7 ± 2.1 (P > 0.05), respectively, compared to control untreated cells. Caspase-3/7 activities in HLE cells were not increased significantly after treatment with DEX at all concentrations tested.
Conclusions: :
This study showed that TA at its clinical dose in both commercial preparation and solubilized form decreases human lens epithelial cell viability and that the caspase-3/7 pathway is involved suggestive of an apoptotic pathway. DEX at its clinical dose does not decrease cell viability nor cause any increase of capase-3/7 activity.